Method of manufacturing articles for which a resistibility against the noxious effect of the aged state is required



Patented Sept. 24, 1929 UNITED-STATES PATENT OFFICE ADOLF FRY, OF ESSEN, GERMANY, ASSIGNOIR T0 FRIED. KRUPP AKTIENGESELL- SCHAFT, OF ESSEN-ON-THE-RUHR, GERMANY METHQD OF MANUFACTURING ARTICLES FOR VVHICHA.

ESISTIIBILITY AGAINST THE NOXIOUS EFFECT OF THE AGED STATE IS REQUIRED No Drawing. Application filed September 8, 1926, Serial No. 134 324, and in Germany April 3, 1926.

A method of manufacturing articlesfor which a resistibility against the noxlous efi ect of the aged state is required.

Many articles made of ingot iron and steel (e. g. boiler plates, high-pressure boilers. tubes, drawn pieces, profile iron etc.) have hitherto, when in an aged state, a very much reduced tenacity when tested in the shape of a notched bar or, in other words, a very low toughness. This tenacity sometimes 5 decreases to about 1,5 mkg./cm. Under the denotion to be in an aged state a stateis to be understood which arises, When a piece made of ingot iron or steel is deformed at 5 about room-temperature and is then for a longer time left to itself. As well known,

the aged state can'be artificially created by reheating an iron or steel body after the said deformation up to a temperature of about 200 C. The aged state also arises, when the deformations of an ingot iron body are effected at temperatures between 150 and 500 C. In this case the aged state is obtained without a leaving of the body for a i longer time in rest or a reheating of the same being necessary. No means are hitherto known to avoid the said detriment with certainty. The consumers therefore contented with the incapacity of the producers to warrant in any way said tenacity of the notched bar when in an aged state.

Now the object of my invention is to avoid this detriment and to enable the producing industry to warrant said tenacity of the material being in an aged state, and this for unusually high values. This efi'ect is obtained according to my invention by manufacturing articles for which a resistibility against the noxious efl'ect of the aged state is required, of an ingotiron or steel which is so highly deoxidized, that the aged state does not effect a substantial decrease of the said tenacity.

It is already known to deoxidize ingot iron or steel by means of aluminium. But hitherto it was'not known that'by a particularly high grade deoxidation the important technical effect is obtained that a substantial .decrease of said tenacity is not caused when thematerial ages. Whether the deoxidation has been effected in the necessary high degree or not, might be ascertained by producing the aged'state in a test piece made of ingot iron or steel and by testing before and after the aging operation by shock tests on the notched piece Whether the tenacity is substantially still the same or not. The ob tained degree of deoxidation might also be ascertained by subjecting an artificially aged test piece, whlch has been subjected to a bend ing test, to a corroding test inorder to produce strain figures by etching. The meaning and effect of etching a test piece and the manner in which this etching is executed, is f. i. dealt with in the Kruppsche 'Monatshefte of 1921, pages 117 to 136. If a care ful etching does not produce strain figures or feebly visible figures only, the degree of deoxidation is sufficient, and this material will undergo, even in an aged state, only a small decrease of said tenacity. The tenacity, measured under equal other conditions, of a normal test piece of 30 mm. 160 (made out of a forged bar having a cross section of 40 mmfi), which is made of ingot iron containing 0,12% of carbon and has an annular notch, is in theaged state yet about to 33 mkg/emF, if this tenacity had been to 35 mkg/cmi", when the material was not yet in an aged state. All the cited values of tenacity have been obtained by measuring at a temperature of +20 C.) This means that there is no essential difference between the tenacity of the material which is in aged state and the tenacity of that which is not in the aged state, the said tenacities being measured under equal other conditions, or, in other words. that the noxious effect of the aged state is avoided. i

In order to realize the high grade deoxi-. dation required for the effect aimed at, besides aluminium other highly deoxidizing means as e. g. titanium, zirconium,vanadium, magnesium and silicon "might be made use .of. Moreover, said high grade deoxidation might be executed by means of carbon in a vacuum. 95 However, a deoxidation performed by means of silicon permits only of a partial eifect to be attained.

When an ingot iron or steel has been hi hly deoxidized according to my invention, it can 100 artificially in advance be'said with security (and thisfis therimportant technical eflect produced by my invention) that the original tenacity of the notched bar will substantially last also in the aged state.

Furthermore, an ingot iron and steel to which up to 5% of nickel, cobalt, chromium, tungsten, vanadium or molybdenum has been added and which has been highly deoxidized according to my invention, presents the advantage that said original tenacity will also not substantially decrease even at low tem- 'p0rs and gases which may cause a feeble reaction, for instance hot caustic soda solution of 45 per cent, alkaline boiler feed water or ammonia gases.

Claims:

, 1. The method of treating iron alloy to impart high tenacity in the aged state which consists in subjecting the alloy to a deoxidizing influence, ascertaining the degree of deoxidation' by testing the tenacity of a sample of said alloy in the aged state, and adjusting the deoxidizing influence in accordance with said test to efi'ect substantially complete deoxidation of the alloy.

'2. The method of treating ingot iron to impart high tenacity in the aged state which consists in subjecting the ingot iron to a deoxidizing influence, ascertaining the degree of deoxidation by' testing the tenacity of a sample of said ingot iron in the aged state, and adjusting the deoxidizing influence in accordance with saidtest to eflect substantially complete deoxidation of the ingot iron.

3. The method of treating steel to impart I high tenacity in the aged state which consists in subjecting the steel to a deoxidizing influ- I l o ence, ascertalnmg the degree of deoxidation by testing the tenacity of a sample of said steel in the aged state, and adjusting the deoxidizing influence in accordance with said test to eflect substantially completedeoxidation of the steel.

4. The method of ascertaining the degree of deoxidation of iron alloys which consists in testing the tenacity of said alloy in the' aged state and comparing the tenacity in the aged state with the tenacity in the normal state;

5. The method of ascertaining the degree of deoxidation of ingot ironwhich consists in testing the tenacity of saidingot iron in the aged state and comparing the tenacity in the aged state with the tenacity in the normal state.

6. The method of ascertaining the'degree of deoxidation of steel which consists in testing the tenacity of said steel in the aged state and comparing the tenacity in the aged state 'with the tenacity in the normal state.

7. The method of treating anralloy' on the iron base to impart high tenacity in the aged state which consists in subjecting the alloy to a deoxidizing influence and ascertaining the exact degree of deoXidation by testing the tenacity of said alloy in the aged state. a 8. The method of making steel alloy containing up to 5% of a metal having the propertiesof nickel which consists in subjecting the alloy to a deoxidizing influence and ascertaining the exact degree of deoxidation by testing the tenacity of said alloy in the aged state.

The foregoing specification signed 'at Cologne, Germany, this 23rd day of August,

ADOLF FRY. 

